Bird cage



FIG. 1 is a front perspective view of a bird cage showing my design;

FIG. 2 is a front view thereof, the back view being a mirror imagethereof;

FIG. 3 is a side view thereof, the opposite side being a mirror imagethereof;

FIG. 4 is a plan view thereof; and,

FIG. 5 is a bottom view thereof.

The ornamental design for a bird cage design, as shown and described.